Power supply 'issues'?

My computer started randomly rebooting yesterday evening. I went
through the ususal process of making sure everything was plugged in
okay, and that everything was at a normal temperature. I also did a
spyware and antivirus scan.

Some of the time it would make it into windows, other times it
wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
install of XP with SP2. I followed some advice in one of the online
forums about disabling system restart at critical failure (or whatever
the proper words are) relating to SP2 after the problem emerged. No
joy. It had been running fine for about a week after the install.

One thing I think is reasonably wierd, that I can't find advice on, is
that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
The PSU is an 350W Enermax, which was expensive at the time, but about
3 years old.

Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
reboots. I have since moved this further down to 100mhz. It seems to
stay up for a little while longer now. Over voltaging the CPU
slightly didn't help. I don't usually overclock/over voltage it.

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In article <> in nz.comp on
Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> says...
> Hi,
>
> My computer started randomly rebooting yesterday evening. I went
> through the ususal process of making sure everything was plugged in
> okay, and that everything was at a normal temperature. I also did a
> spyware and antivirus scan.
>
> Some of the time it would make it into windows, other times it
> wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
> install of XP with SP2. I followed some advice in one of the online
> forums about disabling system restart at critical failure (or whatever
> the proper words are) relating to SP2 after the problem emerged. No
> joy. It had been running fine for about a week after the install.
>
> One thing I think is reasonably wierd, that I can't find advice on, is
> that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
> 4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
> The PSU is an 350W Enermax, which was expensive at the time, but about
> 3 years old.

If you want to be sure, get a digital multimeter and measure the 5V on
one of the drive connectors and also the 12V while you're at it.

Then if it is reading low, disconnect as many peripherals that use the 5V
as possible, and see if it comes up and/or the system becomes more
reliable.

I just worked on a system that would seemingly start up but would not
post, or would just hang while going, cause was found to be one faulty
pin of the ATX power plug that was intermittent, turned out to be the
12V. 5V is very important for the CPU and other chips, usually.
> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
> reboots. I have since moved this further down to 100mhz. It seems to
> stay up for a little while longer now. Over voltaging the CPU
> slightly didn't help. I don't usually overclock/over voltage it.

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On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>Hi,
>
>My computer started randomly rebooting yesterday evening. I went
>through the ususal process of making sure everything was plugged in
>okay, and that everything was at a normal temperature. I also did a
>spyware and antivirus scan.
>
>Some of the time it would make it into windows, other times it
>wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
>install of XP with SP2. I followed some advice in one of the online
>forums about disabling system restart at critical failure (or whatever
>the proper words are) relating to SP2 after the problem emerged. No
>joy. It had been running fine for about a week after the install.
>
>One thing I think is reasonably wierd, that I can't find advice on, is
>that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
>4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
>The PSU is an 350W Enermax, which was expensive at the time, but about
>3 years old.

Only use a Digital Voltmeter, Board monitor programs are not reliable at all,
I have tried 3 and all give different readings..
>Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>reboots. I have since moved this further down to 100mhz. It seems to
>stay up for a little while longer now. Over voltaging the CPU
>slightly didn't help. I don't usually overclock/over voltage it.
>
>I've also tried removing all unessasary components. No joy.
>
>Thanks for your advice!

On Wed, 18 Aug 2004 10:16:38 +1200, Karen Parker
< wrote:
>On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>
>>Hi,
>>
>>My computer started randomly rebooting yesterday evening. I went
>>through the ususal process of making sure everything was plugged in
>>okay, and that everything was at a normal temperature. I also did a
>>spyware and antivirus scan.
>>
>>Some of the time it would make it into windows, other times it
>>wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
>>install of XP with SP2. I followed some advice in one of the online
>>forums about disabling system restart at critical failure (or whatever
>>the proper words are) relating to SP2 after the problem emerged. No
>>joy. It had been running fine for about a week after the install.
>>
>>One thing I think is reasonably wierd, that I can't find advice on, is
>>that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
>>4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
>>The PSU is an 350W Enermax, which was expensive at the time, but about
>>3 years old.
>
>Only use a Digital Voltmeter, Board monitor programs are not reliable at all,
>I have tried 3 and all give different readings..
>
>>Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>>reboots. I have since moved this further down to 100mhz. It seems to
>>stay up for a little while longer now. Over voltaging the CPU
>>slightly didn't help. I don't usually overclock/over voltage it.
>>
>>I've also tried removing all unessasary components. No joy.
>>
>>Thanks for your advice!
>
>
>
>Plus Please try this
>
>http://www.memtest86.com/
>
>
>or this
>
>http://www.simmtester.com/page/products/doc/docinfo.asp
>
>
>As faulty Ram can give the same problems..
>
>You do need to run it over night, if it does not show up on the first pass.

Thanks for the quick responses. I don't think my computer will last
'up' overnight. Even with the 100mhz FSB it's only good for about
10-15 minutes. At 166mhz I'm lucky if I can get to the windows start
up screen.

I don't have access to a multimetre, let alone know how to use one! I
should be able to organise a PSU to try as a replacement. In the
least it should show whether a second PSU has it's 5V reporting below
5V in the bios.

Hmmm, 5V is for supplying the CPU. Some of the first crashes happened
while I was playing Colin McRae 4. It isn't hugely intensive, but it
probably does run the CPU pretty high.

If the PSU doesn't work I'll try to get through some of the memory
tests.

On Wed, 18 Aug 2004 10:38:03 +1200, Mr Bond <> wrote:
>On Wed, 18 Aug 2004 10:16:38 +1200, Karen Parker
>< wrote:
>
>>On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>>
>>>Hi,
>>>
>>>My computer started randomly rebooting yesterday evening. I went
>>>through the ususal process of making sure everything was plugged in
>>>okay, and that everything was at a normal temperature. I also did a
>>>spyware and antivirus scan.
>>>
>>>Some of the time it would make it into windows, other times it
>>>wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
>>>install of XP with SP2. I followed some advice in one of the online
>>>forums about disabling system restart at critical failure (or whatever
>>>the proper words are) relating to SP2 after the problem emerged. No
>>>joy. It had been running fine for about a week after the install.
>>>
>>>One thing I think is reasonably wierd, that I can't find advice on, is
>>>that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
>>>4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
>>>The PSU is an 350W Enermax, which was expensive at the time, but about
>>>3 years old.
>>
>>Only use a Digital Voltmeter, Board monitor programs are not reliable at all,
>>I have tried 3 and all give different readings..
>>
>>>Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>>>reboots. I have since moved this further down to 100mhz. It seems to
>>>stay up for a little while longer now. Over voltaging the CPU
>>>slightly didn't help. I don't usually overclock/over voltage it.
>>>
>>>I've also tried removing all unessasary components. No joy.
>>>
>>>Thanks for your advice!
>>
>>
>>
>>Plus Please try this
>>
>>http://www.memtest86.com/
>>
>>
>>or this
>>
>>http://www.simmtester.com/page/products/doc/docinfo.asp
>>
>>
>>As faulty Ram can give the same problems..
>>
>>You do need to run it over night, if it does not show up on the first pass.
>
>Thanks for the quick responses. I don't think my computer will last
>'up' overnight. Even with the 100mhz FSB it's only good for about
>10-15 minutes. At 166mhz I'm lucky if I can get to the windows start
>up screen.
>
>I don't have access to a multimetre, let alone know how to use one! I
>should be able to organise a PSU to try as a replacement. In the
>least it should show whether a second PSU has it's 5V reporting below
>5V in the bios.
>
>Hmmm, 5V is for supplying the CPU. Some of the first crashes happened
>while I was playing Colin McRae 4. It isn't hugely intensive, but it
>probably does run the CPU pretty high.
>
>If the PSU doesn't work I'll try to get through some of the memory
>tests.

These Ram tests ONLY Run Under DOS, they produce there own Boot Floppy.

Mr Bond wrote:
> Hi,
>
> My computer started randomly rebooting yesterday evening. I went
> through the ususal process of making sure everything was plugged in
> okay, and that everything was at a normal temperature. I also did a
> spyware and antivirus scan.
>
> Some of the time it would make it into windows, other times it
> wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
> install of XP with SP2. I followed some advice in one of the online
> forums about disabling system restart at critical failure (or whatever
> the proper words are) relating to SP2 after the problem emerged. No
> joy. It had been running fine for about a week after the install.
>
> One thing I think is reasonably wierd, that I can't find advice on, is
> that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
> 4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
> The PSU is an 350W Enermax, which was expensive at the time, but about
> 3 years old.
>
> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
> reboots. I have since moved this further down to 100mhz. It seems to
> stay up for a little while longer now. Over voltaging the CPU
> slightly didn't help. I don't usually overclock/over voltage it.
>
> I've also tried removing all unessasary components. No joy.
>
> Thanks for your advice!

For sure sounds like insufficient power to the CPU. I take it you don't have
a little four-pin square connector going from the PSU to the mobo? If you do
the CPU runs off the 12v rail, if you don't it runs off the 5v. I think your
CPU is pulling (or trying to) more power on the 5v rail than the PSU can
supply.
--
~misfit~

"Mr Bond" <> wrote in message
news:...
> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
> reboots. I have since moved this further down to 100mhz. It seems to
> stay up for a little while longer now. Over voltaging the CPU
> slightly didn't help. I don't usually overclock/over voltage it.

Since other people have commented on the RAM and PSU I will ignore those for
now. One thing I would recommend checking is the CPU temperature. I have
found that Athlon XP processors can cause spontaneous system reboot when
they reach a little as 64'C. Check the CPU temperature in the bios. Also
check that the cooler is attached properly, can (and does) spin freely and
that the fins on the heatsink are not clogged up with dust.

On Wed, 18 Aug 2004 13:17:49 +1200, "Andrew Bryson"
<> wrote:
>"Mr Bond" <> wrote in message
>news:...
>
>> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>> reboots. I have since moved this further down to 100mhz. It seems to
>> stay up for a little while longer now. Over voltaging the CPU
>> slightly didn't help. I don't usually overclock/over voltage it.
>
>Since other people have commented on the RAM and PSU I will ignore those for
>now. One thing I would recommend checking is the CPU temperature. I have
>found that Athlon XP processors can cause spontaneous system reboot when
>they reach a little as 64'C. Check the CPU temperature in the bios. Also
>check that the cooler is attached properly, can (and does) spin freely and
>that the fins on the heatsink are not clogged up with dust.
>
>That said, it is most likely the PSU or RAM .
>
>Andrew Bryson
>http://www.bryson.co.nz
>

Thanks for the fresh view . It got as low as 32 degrees when it
was down at 100 fsb. Damn cold last night too. Pretty sure the heat
thing isn't it.

On Wed, 18 Aug 2004 13:12:27 +1200, "~misfit~"
<> wrote:
>Mr Bond wrote:
>> Hi,
>>
>> My computer started randomly rebooting yesterday evening. I went
>> through the ususal process of making sure everything was plugged in
>> okay, and that everything was at a normal temperature. I also did a
>> spyware and antivirus scan.
>>
>> Some of the time it would make it into windows, other times it
>> wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
>> install of XP with SP2. I followed some advice in one of the online
>> forums about disabling system restart at critical failure (or whatever
>> the proper words are) relating to SP2 after the problem emerged. No
>> joy. It had been running fine for about a week after the install.
>>
>> One thing I think is reasonably wierd, that I can't find advice on, is
>> that in my Bios the hardware monitor (Asus A7N8x) reports the 5V to be
>> 4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
>> The PSU is an 350W Enermax, which was expensive at the time, but about
>> 3 years old.
>>
>> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>> reboots. I have since moved this further down to 100mhz. It seems to
>> stay up for a little while longer now. Over voltaging the CPU
>> slightly didn't help. I don't usually overclock/over voltage it.
>>
>> I've also tried removing all unessasary components. No joy.
>>
>> Thanks for your advice!
>
>For sure sounds like insufficient power to the CPU. I take it you don't have
>a little four-pin square connector going from the PSU to the mobo? If you do
>the CPU runs off the 12v rail, if you don't it runs off the 5v. I think your
>CPU is pulling (or trying to) more power on the 5v rail than the PSU can
>supply.

No, my PSU has the connector, but my motherboard doesn't use it. I
had assumed the connector a P4 thing.

Best I think I can do for now is try a different PSU, and if that
doesn't help try and keep it going long enough to get the ram checks
working. It was hard enough getting through the Virus and Spyware
scans!

Mr Bond wrote:
> On Wed, 18 Aug 2004 13:12:27 +1200, "~misfit~"
> <> wrote:
>
>> Mr Bond wrote:
>>> Hi,
>>>
>>> My computer started randomly rebooting yesterday evening. I went
>>> through the ususal process of making sure everything was plugged in
>>> okay, and that everything was at a normal temperature. I also did a
>>> spyware and antivirus scan.
>>>
>>> Some of the time it would make it into windows, other times it
>>> wouldn't get there. My system is a 2500XP, 1gig ram, with a recent
>>> install of XP with SP2. I followed some advice in one of the online
>>> forums about disabling system restart at critical failure (or
>>> whatever the proper words are) relating to SP2 after the problem
>>> emerged. No joy. It had been running fine for about a week after
>>> the install.
>>>
>>> One thing I think is reasonably wierd, that I can't find advice on,
>>> is that in my Bios the hardware monitor (Asus A7N8x) reports the 5V
>>> to be
>>> 4.2V-ish. The 3.3V and 12V look about normal. Is this the problem?
>>> The PSU is an 350W Enermax, which was expensive at the time, but
>>> about 3 years old.
>>>
>>> Initially moving the FSB down to 133mhz (from 166mhz) prolonged the
>>> reboots. I have since moved this further down to 100mhz. It seems
>>> to stay up for a little while longer now. Over voltaging the CPU
>>> slightly didn't help. I don't usually overclock/over voltage it.
>>>
>>> I've also tried removing all unessasary components. No joy.
>>>
>>> Thanks for your advice!
>>
>> For sure sounds like insufficient power to the CPU. I take it you
>> don't have a little four-pin square connector going from the PSU to
>> the mobo? If you do the CPU runs off the 12v rail, if you don't it
>> runs off the 5v. I think your CPU is pulling (or trying to) more
>> power on the 5v rail than the PSU can supply.
>
> No, my PSU has the connector, but my motherboard doesn't use it. I
> had assumed the connector a P4 thing.

It was originally called a 'P4' thing. However, modern PSU's and mobos, both
Intel and AMD, all use them now to supply power to the CPU. The fact that
your PSU has one suggests to me that it's power output is weighted towards
the 12v rail and probably doesn't have enough current capacity on the 5v
rail for a CPU that draws a lot of power.
> Best I think I can do for now is try a different PSU, and if that
> doesn't help try and keep it going long enough to get the ram checks
> working. It was hard enough getting through the Virus and Spyware
> scans!

Look for a PSU with high 5v and 3.3v ratings. As I said, most modern systems
run the CPU from the 12v now and the video card off the 3.3v (which is often
'tied' to the 5v anyway) so they don't have very grunty 5v rails as it's
only really used for the RAM, PCI cards and chipset power. You may need to
go up to a 400 watt - 500 watt plus PSU to get enough of a current rating on
the 5v to power your board. It might actually end up a cheaper option to get
a new mobo that *does* use the 12v for CPU power, high-end PSU's are
expensive.

On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>Hi,
>
>My computer started randomly rebooting yesterday evening. I went
>through the ususal process of making sure everything was plugged in
>okay, and that everything was at a normal temperature. I also did a
>spyware and antivirus scan.
>
Is the CPU fan clogged? Yeah, I know you said that the temps are
normal.

In article ~misfit~ says...
> It was originally called a 'P4' thing. However, modern PSU's and mobos, both
> Intel and AMD, all use them now to supply power to the CPU. The fact that
> your PSU has one suggests to me that it's power output is weighted towards
> the 12v rail and probably doesn't have enough current capacity on the 5v
> rail for a CPU that draws a lot of power.
>
Unfortunately not true. Most PSU with P4 plug still have the emphasis on
the 3.3 and 5 sections.
> Look for a PSU with high 5v and 3.3v ratings. As I said, most modern systems
> run the CPU from the 12v now and the video card off the 3.3v (which is often
> 'tied' to the 5v anyway) so they don't have very grunty 5v rails as it's
> only really used for the RAM, PCI cards and chipset power. You may need to
> go up to a 400 watt - 500 watt plus PSU to get enough of a current rating on
> the 5v to power your board. It might actually end up a cheaper option to get
> a new mobo that *does* use the 12v for CPU power, high-end PSU's are
> expensive.
>
> Cheers,
> --
> ~misfit~
>
Modern Video cards are using 3.3,5 and 12V rails together up to 70W or
more.http://www.xbitlabs.com/articles/video/display/ati-powercons.html

colinco wrote:
> In article ~misfit~ says...
>> It was originally called a 'P4' thing. However, modern PSU's and
>> mobos, both Intel and AMD, all use them now to supply power to the
>> CPU. The fact that your PSU has one suggests to me that it's power
>> output is weighted towards the 12v rail and probably doesn't have
>> enough current capacity on the 5v rail for a CPU that draws a lot of
>> power.
>>
> Unfortunately not true. Most PSU with P4 plug still have the emphasis
> on the 3.3 and 5 sections.

Ok, we've been looking at different PSUs then. I've seen a few that in fact
have two discrete 12v rails.
>> Look for a PSU with high 5v and 3.3v ratings. As I said, most modern
>> systems run the CPU from the 12v now and the video card off the 3.3v
>> (which is often 'tied' to the 5v anyway) so they don't have very
>> grunty 5v rails as it's only really used for the RAM, PCI cards and
>> chipset power. You may need to go up to a 400 watt - 500 watt plus
>> PSU to get enough of a current rating on the 5v to power your board.
>> It might actually end up a cheaper option to get a new mobo that
>> *does* use the 12v for CPU power, high-end PSU's are expensive.
>>
>> Cheers,
>> --
>> ~misfit~
>>
> Modern Video cards are using 3.3,5 and 12V rails together up to 70W or
> more.
> http://www.xbitlabs.com/articles/video/display/ati-powercons.html

Yeah, I wasn't talking about ultra-high-end gaming cards that need seperate
power connectors. Mr. Bond didn't mention he was running a $500 card and I
think he would have mentioned it if he was, especially considering he's only
running a 350W supply. That page you linked states that, without a seperate
power connector going to the card an AGP slot can provide 6A on the 3.3v, 2A
on the 5v and 1A on the 12v rails. It is my understanding that
(non-power-connected) AGP cards can be one of the biggest drains on the 3.3v
rail. That page tends to back that up, thanks.
--
~misfit~

On Wed, 18 Aug 2004 23:23:33 +1200, "~misfit~"
<> wrote:
>colinco wrote:
>> In article ~misfit~ says...
>>> It was originally called a 'P4' thing. However, modern PSU's and
>>> mobos, both Intel and AMD, all use them now to supply power to the
>>> CPU. The fact that your PSU has one suggests to me that it's power
>>> output is weighted towards the 12v rail and probably doesn't have
>>> enough current capacity on the 5v rail for a CPU that draws a lot of
>>> power.
>>>
>> Unfortunately not true. Most PSU with P4 plug still have the emphasis
>> on the 3.3 and 5 sections.
>
>Ok, we've been looking at different PSUs then. I've seen a few that in fact
>have two discrete 12v rails.
>
>>> Look for a PSU with high 5v and 3.3v ratings. As I said, most modern
>>> systems run the CPU from the 12v now and the video card off the 3.3v
>>> (which is often 'tied' to the 5v anyway) so they don't have very
>>> grunty 5v rails as it's only really used for the RAM, PCI cards and
>>> chipset power. You may need to go up to a 400 watt - 500 watt plus
>>> PSU to get enough of a current rating on the 5v to power your board.
>>> It might actually end up a cheaper option to get a new mobo that
>>> *does* use the 12v for CPU power, high-end PSU's are expensive.
>>>
>>> Cheers,
>>> --
>>> ~misfit~
>>>
>> Modern Video cards are using 3.3,5 and 12V rails together up to 70W or
>> more.
>> http://www.xbitlabs.com/articles/video/display/ati-powercons.html
>
>Yeah, I wasn't talking about ultra-high-end gaming cards that need seperate
>power connectors. Mr. Bond didn't mention he was running a $500 card and I
>think he would have mentioned it if he was, especially considering he's only
>running a 350W supply. That page you linked states that, without a seperate
>power connector going to the card an AGP slot can provide 6A on the 3.3v, 2A
>on the 5v and 1A on the 12v rails. It is my understanding that
>(non-power-connected) AGP cards can be one of the biggest drains on the 3.3v
>rail. That page tends to back that up, thanks.

If anyone does have a $500 video card I can have I'd appreciate it. Radeon 9600xt presently.

As an update I swapped in a 320 watt no-name brand PSU that I managed
to acquire temporarily and I don't have a problem no more. Bios
reports the 5V to be 4.85V, so maybe it is under-reporting, but its a
lot higer than the 4.2V the previous PSU was at.

On Wed, 18 Aug 2004 18:03:55 +1200, Enkidu <> wrote:
>On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>
>>Hi,
>>
>>My computer started randomly rebooting yesterday evening. I went
>>through the ususal process of making sure everything was plugged in
>>okay, and that everything was at a normal temperature. I also did a
>>spyware and antivirus scan.
>>
>Is the CPU fan clogged? Yeah, I know you said that the temps are
>normal.
>
>Cheers,
>
>Cliff

Nah, I did a clean out of the fans/heatsinks and switched a few
around. I thought I may be able to reduce the load on the PSU if I
put a bigger/louder fan on the CPU and took off the exhaust and intake
fans. Didn't make any difference but to make my computer louder.

Mr Bond wrote:
> On Wed, 18 Aug 2004 23:23:33 +1200, "~misfit~"
> <> wrote:
>
>> colinco wrote:
>>> In article ~misfit~ says...
>>>> It was originally called a 'P4' thing. However, modern PSU's and
>>>> mobos, both Intel and AMD, all use them now to supply power to the
>>>> CPU. The fact that your PSU has one suggests to me that it's power
>>>> output is weighted towards the 12v rail and probably doesn't have
>>>> enough current capacity on the 5v rail for a CPU that draws a lot
>>>> of power.
>>>>
>>> Unfortunately not true. Most PSU with P4 plug still have the
>>> emphasis on the 3.3 and 5 sections.
>>
>> Ok, we've been looking at different PSUs then. I've seen a few that
>> in fact have two discrete 12v rails.
>>
>>>> Look for a PSU with high 5v and 3.3v ratings. As I said, most
>>>> modern systems run the CPU from the 12v now and the video card off
>>>> the 3.3v (which is often 'tied' to the 5v anyway) so they don't
>>>> have very grunty 5v rails as it's only really used for the RAM,
>>>> PCI cards and chipset power. You may need to go up to a 400 watt -
>>>> 500 watt plus PSU to get enough of a current rating on the 5v to
>>>> power your board. It might actually end up a cheaper option to get
>>>> a new mobo that *does* use the 12v for CPU power, high-end PSU's
>>>> are expensive.
>>>>
>>>> Cheers,
>>>> --
>>>> ~misfit~
>>>>
>>> Modern Video cards are using 3.3,5 and 12V rails together up to 70W
>>> or more.
>>> http://www.xbitlabs.com/articles/video/display/ati-powercons.html
>>
>> Yeah, I wasn't talking about ultra-high-end gaming cards that need
>> seperate power connectors. Mr. Bond didn't mention he was running a
>> $500 card and I think he would have mentioned it if he was,
>> especially considering he's only running a 350W supply. That page
>> you linked states that, without a seperate power connector going to
>> the card an AGP slot can provide 6A on the 3.3v, 2A on the 5v and 1A
>> on the 12v rails. It is my understanding that (non-power-connected)
>> AGP cards can be one of the biggest drains on the 3.3v rail. That
>> page tends to back that up, thanks.
>
> If anyone does have a $500 video card I can have I'd appreciate it
> . Radeon 9600xt presently.
>
> As an update I swapped in a 320 watt no-name brand PSU that I managed
> to acquire temporarily and I don't have a problem no more. Bios
> reports the 5V to be 4.85V, so maybe it is under-reporting, but its a
> lot higer than the 4.2V the previous PSU was at.

This 320W PSU have the four-pin 12v connector? I'd guess not, more power
available on the 5v rail than the other one. Do they have the specs on the
labels? I'd be interested to know what they say for the various rails.

I'd guess that the BIOS is reporting reasonably accurately. You are running
a fairly grunty CPU on fairly low-spec PSUs.
> Thanks for everyones help!

In article ~misfit~ says...
> This 320W PSU have the four-pin 12v connector? I'd guess not, more power
> available on the 5v rail than the other one. Do they have the specs on the
> labels? I'd be interested to know what they say for the various rails.
>
Most PSU seem to have between 30-40A max on +5V. You only have 4 pins in
the ATX connector for +5 which is the limiter. If you try to use more +
5V the plug has a habit of melting.

"Mr Bond" <> wrote in message
news:...
> On Wed, 18 Aug 2004 18:03:55 +1200, Enkidu <> wrote:
>
> >On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
> >
> >>Hi,
> >>
> >>My computer started randomly rebooting yesterday evening. I went
> >>through the ususal process of making sure everything was plugged in
> >>okay, and that everything was at a normal temperature. I also did a
> >>spyware and antivirus scan.
> >>
> >Is the CPU fan clogged? Yeah, I know you said that the temps are
> >normal.
> >
> >Cheers,
> >
> >Cliff
>
> Nah, I did a clean out of the fans/heatsinks and switched a few
> around. I thought I may be able to reduce the load on the PSU if I
> put a bigger/louder fan on the CPU and took off the exhaust and intake
> fans. Didn't make any difference but to make my computer louder.
>
> All fixed though with a swapped PSU.

Kinda curious.

Do you have access to an Oscilloscope or someone that has?

If so have a look at the noise or ripple on the 3.3/5/12 volt lines.

I had a stinker here that measured spot on with a digital multimeter, but
the PC was very flakey starting and the burner wouldn't work etc.
The Oscilloscope showed 350mv (0.35 volt) of noise/ripple on all of the
supply voltages which was way outside the max listed for the burner and
probably for most other bits inside the PC.

Did a quick lashup with some capacitors on the 5 and 12 lines and found
quite an improvement. Reasonable to expect some capacitance on the 3.3v line
would have come close to 'curing' it.

But then something was obviously drifting off inside the supply for it to
have that much noise/ripple so it was better 'binned'.

On Thu, 19 Aug 2004 20:12:12 +1200, "PC" <> wrote:
>
>"Mr Bond" <> wrote in message
>news:...
>> On Wed, 18 Aug 2004 18:03:55 +1200, Enkidu <> wrote:
>>
>> >On Wed, 18 Aug 2004 09:50:37 +1200, Mr Bond <> wrote:
>> >
>> >>Hi,
>> >>
>> >>My computer started randomly rebooting yesterday evening. I went
>> >>through the ususal process of making sure everything was plugged in
>> >>okay, and that everything was at a normal temperature. I also did a
>> >>spyware and antivirus scan.
>> >>
>> >Is the CPU fan clogged? Yeah, I know you said that the temps are
>> >normal.
>> >
>> >Cheers,
>> >
>> >Cliff
>>
>> Nah, I did a clean out of the fans/heatsinks and switched a few
>> around. I thought I may be able to reduce the load on the PSU if I
>> put a bigger/louder fan on the CPU and took off the exhaust and intake
>> fans. Didn't make any difference but to make my computer louder.
>>
>> All fixed though with a swapped PSU.
>
>Kinda curious.
>
>Do you have access to an Oscilloscope or someone that has?
>
>If so have a look at the noise or ripple on the 3.3/5/12 volt lines.
>
>I had a stinker here that measured spot on with a digital multimeter, but
>the PC was very flakey starting and the burner wouldn't work etc.
>The Oscilloscope showed 350mv (0.35 volt) of noise/ripple on all of the
>supply voltages which was way outside the max listed for the burner and
>probably for most other bits inside the PC.
>
>Did a quick lashup with some capacitors on the 5 and 12 lines and found
>quite an improvement. Reasonable to expect some capacitance on the 3.3v line
>would have come close to 'curing' it.
>
>But then something was obviously drifting off inside the supply for it to
>have that much noise/ripple so it was better 'binned'.
>
>A new P/S 'fixed' the problem.
>
>Cheers
>Paul
>

You need to be very careful when measuring noise on PSU Lines, as its so easy
to pick up noise in the leads to the Scope, Must use Very short earth lead,
and a scope probe, plus the problems when the Scope is earthed, ie, earth
loops..

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